Larger Future Intensification of Rainfall in the West African Sahel in a Convection‐Permitting Model

Monsoon rainfall in West Africa mostly comes from mesoscale convective systems, which are not well represented by standard convection‐parameterized regional climate models (RCMs). We use a 4.5 km resolution convection‐permitting RCM (CP4A) which has a good representation of these processes in the Sa...

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Bibliographic Details
Published in:Geophysical research letters 2019-11, Vol.46 (22), p.13299-13307
Main Authors: Berthou, S., Kendon, E. J., Rowell, D. P., Roberts, M. J., Tucker, S., Stratton, R. A.
Format: Article
Language:English
Subjects:
Agriculture
Climate change
Climate models
Convection
convection‐permitting model
Dry spells
Duration
extreme rainfall
Extreme weather
Hydrology
Mesoscale convective systems
Monsoon rainfall
Rain
Rainfall
rainfall intensification
Rainfall intensity
Rainfall variability
Regional climate models
Regional climates
Signal processing
West Africa
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Summary:Monsoon rainfall in West Africa mostly comes from mesoscale convective systems, which are not well represented by standard convection‐parameterized regional climate models (RCMs). We use a 4.5 km resolution convection‐permitting RCM (CP4A) which has a good representation of these processes in the Sahel. By comparing the climate change signals of CP4A and a standard RCM (R25), we find that changes in mean rainfall and wet‐day frequency are linearly related. However, rainfall intensity changes are independent. Intensification of rainfall is larger in CP4A and happens in regions of both increasing and decreasing mean rainfall. Rainfall from extreme events increases by a factor of 5 to 10 in CP4A, compared to 2 to 3 in R25. CP4A also shows larger changes in intraseasonal rainfall variability, dry spells, and short and long duration extreme rainfall than R25, all of which are relevant for hydrology and agriculture. Key Points Mean rainfall changes are similar in a convection‐permitting compared to a parameterized model, but intensification of rainfall is stronger Rainfall from extreme events increases by a factor of 5 to 10 in a convection‐permitting model, against 2 to 3 in a parameterized model The convection‐permitting model shows a larger amplitude of change for 5 out of 6 agriculture and hydrology relevant metrics in the Sahel
ISSN:0094-8276
1944-8007
DOI:10.1029/2019GL083544